Ghost of the Desert: The Pronghorn

by Ron Harton


The wind sweeps across the desert and sculpts our parkas around our backs. We try to hold our binoculars steady while we scan the scrub along the top of the bajada. There. Definitely not a deer! A pronghorn, also known as the American antelope. We both see him at the same time. His tan back, white neck collars, white underparts and rump blend in well with the desert. It’s a male. We can tell by the long horns and black patches on his cheeks. He saw us long before we saw him, though, and he’s looking back over his shoulder at us in characteristic curiosity. Then he turns to go over the rise. We just catch a glimpse of his white rump as he vanishes in the brush.

The pronghorn we saw years ago while backpacking in a remote part of Organ Pipe Cactus National Monument was probably a Sonoran pronghorn, an endangered subspecies of the American pronghorn, Antilocapra americana, which is found throughout the West. There are only about two hundred Sonoran pronghorns left now in the United States. They move back and forth between northern Mexico and the Cabeza Prieta National Wildlife Refuge in southwest Arizona, traveling through Organ Pipe Cactus National Monument. Arizona also has a small population of Chihuahuan or Mexican pronghorn near its southeast border with Mexico. The American pronghorn is the type seen in Nevada, northern Arizona, and throughout the western states and Central Plains. Neither the Mexican nor the American pronghorn is considered endangered.

Although the pronghorn is often called an antelope, it’s not in the same family as the African or Asian antelopes. It’s in a class by itself. In fact, it’s the only animal of its type in the world. Its scientific name, Antilocapra, means antelope-goat, but that doesn’t come close to describing this amazing animal. The name pronghorn is more appropriate. Pronghorn obviously refers to the animal’s unique “pronged” or “forked” horns, and they are special. They’re horns, not antlers, but they are branched like antlers. Pronghorns are the only animal with branched horns and the only animal to shed its horns. Both males and females have horns, although the male’s horns are much longer. The female’s horns are just two or three inches in length while the male’s horns may be twelve to sixteen inches. The male’s horns curve backward and point inward at the tip. They have the prong, a small fork a little over half way up the horn. The horns have two parts–an inner bony core and an outer sheath that looks like hardened hair. The outer sheath is shed every fall and grows back in the spring. The remaining cores are sharp pointed cones that extend a few inches from the head.

Pronghorns are the size and shape of small deer. The bucks weigh between 100-150 pounds and the does are slightly smaller. Their outer hair is coarse and long. Underneath it they have a thin layer of very fine fur. Pronghorns loosen or tighten the outer hair to adjust their body temperature. Their coloration pattern of tan and white helps them blend in with the landscape. The Ogallala Sioux name for pronghorns means “little pale deer” and the Mexicans refer to it as berrendo or “pinto.” The pronghorn’s camouflage helped earn them the nickname “prairie ghost.” It’s not only their color that helps them disappear, though, it’s also their speed.

The pronghorn is famous for its speed. In fact, it is the fastest North American mammal and the second fastest in the world. Adults are able to cruise for long distances at forty miles an hour and reach a top speed of sixty mph. Jack Schaefer, author of the Western classic, Shane, calls the pronghorn “the perfect running machine.” Schaefer compares the pronghorn’s speed to a horse by noting that if a pronghorn were entered in the Kentucky Derby, it would cross the finish line before the horses reached the halfway mark. When pronghorns run, their upper body stays smooth and level. Their powerful legs act like shock absorbers and a suspension system. Their front hoofs are larger than their rear ones. These large front feet provide stability while running over rough ground. They seem to glide smoothly over even the roughest terrain. An early naturalist, Josiah Gregg, said pronghorn look like they are ice skating over the desert. At top speed their leaping strides can cover fourteen feet.

Pronghorns also have remarkable eyesight. Their large, bulging eyes are set on the side of their heads where they provide a wideangle view of the world. The power of their eyes match the 8X binoculars we use to view them. Pronghorns depend on their vision and their speed to escape their main enemy–humans. They are hunted throughout their range, even in some areas which have been designated to “protect” them. At one time over 40 million pronghorns roamed the West. They once were as numerous as the buffalo. Estimates of their peak population run as high as 100 million. Hunting reduced the population to about 20,000 by the early 1900’s. Careful management, primarily for sport hunting, has increased their numbers. It is estimated there are now over a million pronghorns in the United States and Canada. They are a common sight in the northern plains and Rocky Mountain states.

Pronghorns were once common in California, too. Herds roamed the Mojave and Colorado deserts and the Central Valley. The last known report of a wild pronghorn was in 1954 in Fresno County. Friends reported seeing two pronghorns in the grasslands near Avenal a few years ago. However, these may have owed their presence to stocking by outfitters who bring clients to the foothills to hunt. Pronghorns can still be found in northeastern California, particularly in Lassen and Modoc counties.

Pronghorns like to live in open country. The best pronghorn country is open, rolling terrain with low vegetation. They are at home in hot summers and harsh winters. Pronghorns don’t like fences. They can leap, but seem reluctant to do so. They may be stymied by even short fences. They are more likely to try to crawl under a barbed wire fence than to jump over it. A barbed wire fence or sheep fence can block pronghorns from food or shelter and cause their deaths in winter. A June 1997 Desert Survivor service trip removed dangerous fences from the Sheldon Antelope Refuge in northern Nevada.

When pronghorns are alarmed, they raise the white hair on their rump to signal the herd or small family group of approaching danger. In the herds, sentinels take turns standing guard while the others feed. Their natural curiosity causes them to check out the intruder carefully before they run. They will sometimes even move toward a person who is half hidden in order to investigate. Hunters have sometimes used the trick of waving a handkerchief slowly back and forth from behind some brush to lure a pronghorn into range. When they sense danger, though, they depend on their speed to carry them to safety. The does usually lead the flight. The does run first with their heads up, while the buck brings up the rear with head lowered.

Like deer, pronghorns browse instead of graze. Their diet consists mainly of shrubs, forbs or broadleaf weeds, and cactus. They don’t eat much grass unless there is a shortage of the things they prefer. Pronghorns will even eat plants considered poisonous or undesirable for cattle. Their food includes larkspur, woolly senecio, paper flower, rubber weed, goldenrod, cutleaf daisy, white daisy, stickleaf, cockle burs, needle-and-thread grass, yucca, snakeweed, broom-rape, sagebrush, bitterbrush, rabbitbrush, Russian thistle, winterfat, chamiso, juniper, and saltbrush. They feed during the night as well as the day, but are most active during the evening and morning hours. Pronghorns are cud-chewers. They have a four-chambered stomach, and spend much of their rest time ruminating.

A typical day for a pronghorn begins shortly after dawn. They feed for several hours, and then lie down to rest for about an hour. When resting, they face in different directions to watch for danger. They feed again through morning and take an extended rest period at midday. Afternoon feedings are also interspersed with rest periods, followed by steady feeding until nightfall. This pattern of feeding and rest is repeated at night. However, at night, the periods of rest are longer. Pronghorns drink once a day when water is available. They may go for days or even weeks without drinking, attaining moisture from their food.

American pronghorns breed in late summer to early fall. The bucks stage mock battles, charging each other with lowered horns. Only dominant bucks breed with the does. Pronghorns have a well-developed social structure. The bucks gather small family groups of two to fourteen does. The bachelor bucks gather in small groups and stay to themselves. Sometimes they follow the family groups at a distance. In late winter and early spring, the does begin to separate from the group and seek a place where they can give birth. They find a place where they can hide the fawns when they are born. The bucks move off to form their own groups.

The fawns, often twins, are born after about 250 days, between late February and early June. The mother hides her fawns when she leaves to feed, returning regularly throughout the day to nurse them. The young weigh only about five to eight pounds when born, but by a week old, they are already running around and beginning to eat vegetation. At a week old, a pronghorn baby can outrun an adult human. Pronghorns grow up quickly. It is not unusual for females to mate in the fall of the year that they were born. When the fawns are old enough to travel, the does regroup into small herds.

The pronghorn population is scattered all over the West. One good place to see them is the Sheldon-Hart Mountain National Wildlife Complex in northern Nevada and eastern Oregon. The Sheldon National Wildlife Range in northern Nevada and Hart Mountain National Antelope Refuge were established to preserve American antelope. The best time to visit is in May through early summer. During the winter and early spring the roads may be impassable. Also in Nevada, check out the Fish Springs National Wildlife Refuge, and Ruby Lake where they have been reintroduced. Pronghorns also live on the Kaibab Plateau in Northern Arizona. Trips to Nevada wilderness provide good opportunities to look for pronghorns, the “Ghosts of the Desert.”
 

BIBLIOGRAPHY


Byers, John A. American Pronghorn: Social Adaptations and Ghosts of Predators Past. Chicago: University of Chicago Press, 1998.

Jaegar, Edmund C. Desert Wildlife. Stanford: Stanford University, 1961.

Schaeffer, Jack. An American Bestiary. Boston: Houghton Mifflin Company, 1975.

Van Wormer, Joe. The World of the Pronghorn. Philadelphia: J .B. Lippincott, 1969.

Wilburn, Jack. Wild Animals of California and the West. Sacramento: Cougar Books, 1979.